Control network for brake system

ABSTRACT

An electrically controlled braking system includes a control unit and first and second brake components responsive to control signals indicative of demand for braking generated by the control unit. A first control network electrically connects the control unit and the first brake component, and is adapted to transmit the control signals from the control unit to the first brake component. A second control network electrically connects the control unit and the second brake component, and is adapted to transmit the control signals from the control unit to the second brake component. An auxiliary control link electrically connects the first control network and the second control network, the auxiliary control link being adapted to transmit the control signals between the first control network and the second control network when a failure occurs in one of the first control network or the second control network.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 10/673,782, filed Sep. 29, 2003, now U.S. Pat. No. 7,150,506.

FIELD OF THE INVENTION

The present invention relates generally to an electrically controlledbraking system which is intended for use with wheeled vehicles, and moreparticularly to a control network for such a braking system whichincorporates enhanced safety features.

BACKGROUND OF THE INVENTION

Traditional braking systems for motor vehicles include conventionalhydraulic or pneumatic brakes associated with two or more wheels of thevehicle. Such conventional brakes are actuated by pressurized fluid orcompressed air. When actuated, the brakes exert a force on a disk ordrum which spins in conjunction with the wheel of the vehicle in orderto create frictional forces which resist rotation of the wheel.Traditionally, control signals have been transmitted to each of thebrake system's actuators mechanically, or by a hydraulic or pneumaticcontrol circuit. However, it has more recently been proposed to employ acentralized control unit to generate electronic control signals and touse such electronic control signals to control actuation of a vehicle'sbrakes. This type of electronic control scheme has become even moreprevalent in view of modern brake systems which now often include notonly conventional hydraulic or pneumatic brake actuator functionality,but also supplemental electronic functions such as antilock protection(ABS) and/or electronic braking force distribution (EBV) between thefront and rear axles.

U.S. Pat. No. 6,354,671 discloses a brake system in which electronicsignals are used to at least partially control actuation of a vehicle'sbrakes. However, as recognized in the patent, brake system failure dueto failure of the electronic control unit is a significant risk. Assuch, system redundancy is provided in the form of a back-up pneumaticcontrol circuit. Should the electronic control unit malfunction, thebraking system is controlled by the back-up pneumatic control circuit inmuch the same way as traditional brake systems operate. However, such asystem suffers from a number of disadvantages. Providing a back-uppneumatic control circuit greatly complicates the braking system andincreases the costs thereof. Moreover, when operating in the back-upmode, the advanced functionality of the electronic control system islost. As such, providing a pneumatic back-up system defeats many of theadvantages of providing an electronic control circuit in the firstplace.

U.S. Pat. No. 6,209,966 obviates some of the problems associated withproviding a back-up pneumatic control circuit by employing twoelectronic control units, which operate independently of each other, andwhich provide control signals to a brake cylinder assigned to a wheeland a braking pressure modulator valve which is fluid-connected to thebrake cylinder. The braking pressure modulator has a first electricactuating element, which can be activated by a first of the two controlunits, and a second electric actuating element which acts in the samedirection when activated as the first electric actuating element. Thesecond electric actuating element can be activated by the secondelectronic control unit at the same time as the first electric actuatingelement is being activated by the first electronic control unit. Thus,system redundancy is provided by providing two separate electroniccontrol units, each of which controls one of two separate electricactuating elements associated with each wheel.

While U.S. Pat. No. 6,209,966 obviates some of the problems associatedwith providing a back-up pneumatic control circuit, it suffers fromdisadvantages of its own. The braking system disclosed in the '966patent would require two separate electronic actuating elementsassociated with each wheel. This requirement, however, needlesslycomplicates and increases the cost of the system. This is true becausecontrol problems, when they arise, are generally caused by a malfunctionin the control unit and/or the control network by which control signalsare transmitted to the actuating elements, not by failure of theactuating elements themselves. As such, providing two actuating elementsfor each wheel would not significantly enhance safety of the brakingsystem. Moreover, because both electronic control networks (i.e., thecontrol networks associated with each electronic control unit) aredirectly connected to actuating elements at each wheel, it is possiblefor an external catastrophic event, such as a tire explosion, in thevicinity of one of the wheels to cut the network cabling and/or cause ashort-circuit in both control networks, thereby causing the entire brakesystem to fail.

It has also been suggested to create a redundant electronic controlsystem where two separate control networks are employed. Such a system100, shown in FIG. 1, employs one or more central control units 102provided to control two or more brake assemblies 104, 106, 108, 110,112, 114, each having a brake actuator 116 incorporating an electroniccontrol unit 118. Central control unit or units 102 is or are inelectrical communication with the electronic control unit 118 of each ofbrake assemblies 104, 106, 108, 110, 112, 114 via at least twoelectronic control networks 120, 122. As seen in FIG. 1, all ofelectronic control units 118 of all brake assemblies 104, 106, 108, 110,112, 114 are connected to each electronic control network 120, 122. Byproviding such an arrangement, should one electronic control networkfail, the other electronic control network would theoretically maintaincontrol of all brake assemblies.

However, this arrangement suffers from disadvantages similar to thosesuffered by U.S. Pat. No. 6,209,966 discussed above. More specifically,because both electronic control networks 120, 122 are directlyelectrically connected to electronic control units 118 of all brakeassemblies 104, 106, 108, 110, 112, 114, it is possible for an externalcatastrophic event, such as a tire explosion, in the vicinity of one ofthe brake assemblies to cut the network cabling and/or cause ashort-circuit in both control networks 120, 122, thereby causing theentire brake system to fail.

What is desired, therefore, is an electrically controlled braking systemwhich is intended for use with wheeled vehicles, which incorporatesenhanced safety features, which employs system redundancy in case ofpartial system failure, which is relatively uncomplicated and lesscostly as compared to known systems, and which is not prone to completesystem failure in the case of an external catastrophic event.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide anelectrically controlled braking system which is intended for use withwheeled vehicles.

Another object of the present invention is to provide an electricallycontrolled braking system having the above characteristics and whichincorporates enhanced safety features.

A further object of the present invention is to provide an electricallycontrolled braking system having the above characteristics and whichemploys system redundancy in case of partial system failure.

Still another object of the present invention is to provide anelectrically controlled braking system having the above characteristicsand which is relatively uncomplicated and less costly as compared toknown systems.

Yet a further object of the present invention is to provide anelectrically controlled braking system having the above characteristicsand which is not prone to complete system failure in the case of anexternal catastrophic event.

These and other objects of the present invention are achieved in oneembodiment by provision of an electrically controlled braking systemincluding at least one control unit, the at least one control unitgenerating control signals indicative of demand for braking, a firstbrake component responsive to the control signals generated by the atleast one control unit, a second brake component responsive to thecontrol signals generated by the at least one control unit. A firstcontrol network electrically connects the at least one control unit andthe first brake component, the first control network being adapted totransmit the control signals from the at least one control unit to thefirst brake component. A second control network electrically connectsthe at least one control unit and the second brake component, the secondcontrol network being adapted to transmit the control signals from theat least one control unit to the second brake component. An auxiliarycontrol link electrically connects the first control network and thesecond control network, the auxiliary control link being adapted totransmit the control signals between the first control network and thesecond control network when a failure occurs in one of the first controlnetwork or the second control network.

In some embodiments, the at least one control unit comprises two controlunits, one of the two control units is electrically connected to thefirst control network, and another of the two control units iselectrically connected to the second control network. In someembodiments, the at least one control unit comprises a single controlunit, and the single control unit is electrically connected to both thefirst control network and the second control network. In someembodiments, the at least one control unit comprises two control units,and each of the two control units is electrically connected to both thefirst control network and the second control network.

In some embodiments, the braking system further includes a third brakecomponent responsive to the control signals generated by the at leastone control unit, the third brake component electrically connected tothe second control network, a fourth brake component responsive to thecontrol signals generated by the at least one control unit, the fourthbrake component electrically connected to the first control network, andthe first brake component and the second brake component are located ona tractor and the third brake component and the fourth brake componentare located on a trailer connected to the tractor. In certain of theseembodiments, the braking system further includes a trailer link by whichthe tractor and the trailer are connected, and the auxiliary controllink comprises part of the trailer link. In certain of theseembodiments, the trailer link comprises an adapter connectable betweenthe tractor and the trailer.

In some embodiments, the braking system further includes a fifth brakecomponent responsive to the control signals generated by the at leastone control unit, the fifth brake component electrically connected tothe second control network, a sixth brake component responsive to thecontrol signals generated by the at least one control unit, the sixthbrake component electrically connected to the first control network, andthe fifth brake component and the sixth brake component are located thetrailer.

In some embodiments, each of the first brake component and the secondbrake component comprises a brake actuator comprising an electricalcontrol unit. In some embodiments the first brake component and thesecond brake component are actuated by a force selected from the groupconsisting of an electrical force, a hydraulic force, a pneumatic forceand combinations of these. In some embodiments, the first brakecomponent and the second brake component are disposed on a common axleof a vehicle. In some embodiments, the at least one control unit furthercontrols functions a vehicle system selected from the group consistingof an antilock brake system, an electronic braking force distributionsystem, a vehicle suspension system, a dynamic stability system andcombinations of these. In some embodiments, control signals to whichboth the first brake component and the second brake component areresponsive are transmitted over both the first control network and thesecond control network.

In accordance with another embodiment of the present invention, anelectrically controlled braking system includes at least one controlunit, the at least one control unit generating control signalsindicative of demand for braking, a first brake component, a secondbrake component, a third brake component, a fourth brake component, afifth brake component and a sixth brake component, each of which isresponsive to the control signals generated by the at least one controlunit. The first and second brake components are located on a tractor andthe third, fourth, fifth and sixth brake components are located on atrailer connected to the tractor. A first control network electricallyconnects the at least one control unit and the first brake component,the fourth brake component and the sixth brake component, the firstcontrol network being adapted to transmit the control signals from theat least one control unit to the first, fourth and sixth brakecomponents. A second control network electrically connects the at leastone control unit and the second brake component, the third brakecomponent and the fifth brake component, the second control networkbeing adapted to transmit the control signals from the at least onecontrol unit to the second, third and fifth brake components. Anauxiliary control link electrically connects the first control networkand the second control network, the auxiliary control link being adaptedto transmit the control signals between the first control network andthe second control network when a failure occurs in one of the firstcontrol network or the second control network.

In some embodiments, the braking system further includes a trailer linkby which the tractor and the trailer are connected, and the auxiliarycontrol link comprises part of the trailer link. In certain of theseembodiments, the trailer link comprises an adapter connectable betweenthe tractor and the trailer.

In accordance with another embodiment of the present invention, anelectrically controlled braking system includes at least one controlunit, the at least one control unit generating control signalsindicative of demand for braking, a first brake component responsive tothe control signals generated by the at least one control unit, and asecond brake component responsive to the control signals generated bythe at least one control unit. A control network electrically connectsthe at least one control unit and the first brake component, and thefirst brake component and the second brake component, the controlnetwork being adapted to transmit the control signals from the at leastone control unit to the first brake component and the second brakecomponent. An auxiliary control link electrically connects the at leastone control unit and the second brake component, the auxiliary controllink being adapted to transmit the control signals between the at leastone control unit and the second brake component when a failure occurs inthe control network.

In some embodiments, the at least one control unit comprises a singlecontrol unit, and the single control unit is electrically connected tothe control network. In some embodiments, the at least one control unitcomprises two control units, and each of the two control units iselectrically connected to the control network. In some embodiments, thebraking system further includes a third brake component and a fourthbrake component responsive to the control signals generated by the atleast one control unit, the third brake component and the fourth brakecomponent being electrically connected between the first brake componentand the second brake component. In certain of these embodiments, thebraking system further includes a fifth brake component and a sixthbrake component responsive to the control signals generated by the atleast one control unit, the fifth brake component and the sixth brakecomponent being electrically connected between the first brake componentand the second brake component.

In some embodiments, each of the first brake component and the secondbrake component comprises a brake actuator comprising an electricalcontrol unit. In some embodiments, the first brake component and thesecond brake component are actuated by a force selected from the groupconsisting of an electrical force, a hydraulic force, a pneumatic forceand combinations of these. In some embodiments, the first brakecomponent and the second brake component are disposed on a common axleof a vehicle. In some embodiments, the at least one control unit furthercontrols functions a vehicle system selected from the group consistingof an antilock brake system, an electronic braking force distributionsystem, a vehicle suspension system, a dynamic stability system andcombinations of these.

In accordance with another embodiment of the present invention, anelectrically controlled braking system includes at least one controlunit, the at least one control unit generating control signalsindicative of demand for braking, and a plurality of brake componentsresponsive to the control signals generated by the at least one controlunit. A control network electrically connects the at least one controlunit and the plurality of brake components in series in a communicationschain, the control network being adapted to transmit the control signalsin a first direction along the communications chain from the at leastone control unit to a first brake component in the communications chain,through any intermediate brake components in the communications chainand to a last brake component in the communications chain. An auxiliarycontrol link electrically connects the at least one control unit and thelast brake component in the communications chain, the auxiliary controllink being adapted to transmit the control signals from the at least onecontrol unit to the last brake component in the communications chain andthrough the control network when a failure occurs in the controlnetwork, and in a second direction along the communications chainopposite to the first direction.

In some embodiments, the plurality of brake components comprises fourbrake components. In some embodiments, the plurality of brake componentscomprises six brake components. In some embodiments, the at least onecontrol unit comprises a single control unit, and the single controlunit is electrically connected to the control network. In someembodiments, the at least one control unit comprises two control units,and each of the two control units is electrically connected to thecontrol network. In some embodiments, each of the plurality of brakecomponents comprises a brake actuator comprising an electrical controlunit. In some embodiments, each of the plurality of brake components isactuated by a force selected from the group consisting of an electricalforce, a hydraulic force, a pneumatic force and combinations of these.In some embodiments, the at least one control unit further controlsfunctions a vehicle system selected from the group consisting of anantilock brake system, an electronic braking force distribution system,a vehicle suspension system, a dynamic stability system and combinationsof these.

The invention and its particular features and advantages will becomemore apparent from the following detailed description considered withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an electrically controlled braking systemin accordance with a known prior art design;

FIG. 2 is a schematic view of an electrically controlled braking systemin accordance with an embodiment of the present invention;

FIG. 3 is a schematic view illustrating in more detail certain aspectsof a particular embodiment of how the electrically controlled brakingsystem of FIG. 2 may be implemented;

FIG. 4 is a schematic view of an electrically controlled braking systemin accordance with another embodiment of the present invention; and

FIG. 5 is a schematic view of an electrically controlled braking systemin accordance with another embodiment of the present invention.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

Referring to FIG. 2, an electrically controlled braking system 10 inaccordance with the present invention is shown. Braking system 10includes at least one control unit 12 which generates control signals.Braking system 10 also includes a plurality of brake components 14, 16,18, 20, 22, 24. While six brake components 14, 16, 18, 20, 22, 24 areshown in FIG. 2, it should be understood that braking system 10 mayinclude a greater or lesser number of brake components. It is desirable,although not strictly necessary, that an even number of brake componentsare provided, and that the brake components are treated as pairs. Forexample, the brake components associated with the pair of wheels on eachaxle may be treated as a pair. In FIG. 2, first brake component 14 ispaired with second brake component 16, third brake component 18 ispaired with fourth brake component 20, and fifth brake component 22 ispaired with sixth brake component 24.

Each of brake components 14, 16, 18, 20, 22, 24 is responsive to thecontrol signals generated by control unit(s) 12. More particularly, eachof brake components 14, 16, 18, 20, 22, 24 includes a brake actuator 26incorporating an electronic control unit 28 which electronic controlunit 28 causes brake actuator 26 to operate in response to the controlsignals. As such electronically controllable brake components are knownin the art, a detailed discussion of the operation thereof is notpresented herein. Each of brake components 14, 16, 18, 20, 22, 24 may beactuated by electrical force, hydraulic force, pneumatic force,combinations of these, and/or by any other appropriate force.

Braking system 10 includes at least two control networks fortransmitting control signals from control unit(s) 12 to each of brakecomponents 14, 16, 18, 20, 22, 24, with some of brake components 14, 16,18, 20, 22, 24 being electrically connected to control unit(s) 12 viaone control network and others of brake components 14, 16, 18, 20, 22,24 being electrically connected to control unit(s) 12 via another orother control network(s). Preferably, each one of each pair of brakecomponents is connected to a different control network.

In braking system 10 shown in FIG. 2, two control networks 30, 32 areprovided. First control network 30 electrically connects control unit(s)12 with first brake component 14, third brake component 18 and fifthbrake component 22 (i.e., one of each pair of brake components). Firstcontrol network 30 is adapted to transmit the control signals fromcontrol unit(s) 12 to first brake component 14, third brake component 18and fifth brake component 22. Second control network 32 electricallyconnects control unit(s) 12 with second brake component 16, fourth brakecomponent 20 and sixth brake component 24 (i.e., the other one of eachpair of brake components not electrically connected to first controlnetwork 30). Second control network 32 is adapted to transmit thecontrol signals from control unit(s) 12 to second brake component 16,fourth brake component 20 and sixth brake component 24.

It is desirable that no brake component is directly electricallyconnected to both of first control network 30 and second control network32. This is true so as to reduce the likelihood that an externalcatastrophic event, such as a tire explosion, in the vicinity of one ofthe brake components cut the network cabling and/or causes ashort-circuit in both control networks 30, 32, thereby causing theentire brake system 10 to fail. For example, an external catastrophicevent occurring in the vicinity of first brake component 14 may causedamage to first control network 30, thereby causing first controlnetwork 30 to be shorted and fail. However, because second controlnetwork 32 is not directly electrically connected to first brakecomponent 14, such an external catastrophic event likely would not causedamage to second control network 32, and second control network 32 wouldstill function.

Brake system 10 also includes auxiliary control links between each ofthe pairs of brake components, which auxiliary control links areactivatable to electrically connect the pairs of brake components when afailure occurs in one of the control networks 30, 32. The auxiliarycontrol links are adapted to transmit the control signals between eachof the brake components forming each pair of brake components when sucha failure occurs. In the embodiment shown in FIG. 2, three suchauxiliary control links 34, 36, 38 are shown. First auxiliary controllink 34 electrically connects first brake component 14 and second brakecomponent 16, second auxiliary control link 36 electrically connectsthird brake component 18 and fourth brake component 20, and thirdauxiliary control link 38 electrically connects fifth brake component 22and sixth brake component 24.

It should be recognized that for system 10 to properly function, controlsignals for all brake components 14, 16, 18, 20, 22, 24 should betransmitted over both control networks 30, 32, not just the controlsignals for the brake components directly connected to each individualcontrol network 30, 32. For example, although first brake component 14is not directly connected to second control network 32, the controlsignals for first brake component 14 should be transmitted over secondcontrol network 32, so that in the event of a failure of first controlnetwork 30 (to which first brake component 14 is attached), controlsignals may be transmitted to first brake component 14 through secondcontrol network 32 and second brake component 16 via first auxiliarycontrol link 34.

Thus, as discussed in the above example, suppose that an externalcatastrophic event occurs in the vicinity of first brake component 14which causes damage to first control network 30, thereby causing firstcontrol network 30 to be shorted and/or fail. Because second controlnetwork 32 is not directly electrically connected to first brakecomponent 14, such an external catastrophic event likely would not causedamage to second control network 32, and second control network 32 wouldstill function. Since first brake component 14 would no longer bereceiving control signals through first control network 30, firstauxiliary control link 34 would attempt to supply control signals tofirst brake component 14 from second brake component 16. Of course, dueto the hypothetical external catastrophic event, first brake component14 may be damaged or destroyed and not function properly, and/or firstauxiliary control link 34 may be damaged. Thus, first brake component 14may not be operational. However, third brake component 18 and fifthbrake component 22 are likely not damaged—they are simply no longerreceiving control signals through the failed first control network 30.As such, control signals supplied to third brake component 18 and fifthbrake component 22 from fourth brake component 20 and sixth brakecomponent 24 through second auxiliary control link 36 and thirdauxiliary control link 38 respectively could be used to control thirdbrake component 18 and fifth brake component 22.

Thus, system redundancy is provided, while at the same time isolation ofthe control networks 30, 32 from one another is maintained by providingconnection between brake components on different control networks 30, 32by way of a buffer (i.e., auxiliary control links 34, 36, 38). Thus, itis extremely unlikely that both control networks 30, 32 will fail. Atthe same time, if one of them does fail, control of at least some of thebrake components on the failed control network can still be maintained.

In some cases, it may be desirable for two control units 12 to beprovided. When such is the case, one of control units 12 may beelectrically connected to first control network 30, while the other ofcontrol units 12 may be electrically connected to second control network32. Alternatively, in order to maintain true redundancy (for example, ifone of control units 12 fails), each of the two control units 12 may beelectrically connected to both control networks 30, 32. In other cases,it may be desirable for a single control unit 12 to be provided, whichcontrol unit 12 may be electrically connected to both control networks30, 32. Of course, in any case where control unit(s) 12 is/are connectedto both control networks 30, 32, it would be desirable to providecontrol unit(s) 12 with safeguard measures to ensure that shorting orother failure of one control network 30, 32 does not short or otherwisecause a failure of the entire control unit(s) 12.

In addition to controlling standard braking operations, control unit(s)12 may control various additional braking functions, such as antilockbrake systems (ABS) and electronic braking force distribution (EBV)systems, as well as other vehicle systems, such as vehicle suspensionand dynamic stability systems.

Referring now to FIG. 3, an embodiment of how the system 10 of FIG. 2may be implemented is shown. More specifically, a “dual link” system isbased upon the concept of treating the brake components of each axle asa pair. The term “dual link” refers to the connection between the leftand right side brake actuator in this pair. The dual link is applicablefor power supply, digital communication and single/multiple sensorinformation. The design of the local electronics according to oneembodiment of a dual link system 300 is shown in FIG. 3.

The dual link system 300 at a local level may provide a safe switch onfunction of the secondary supply voltage. Switch on (with abi-directional switch or dual unidirectional switches) is to bedetermined by the software in both brake units in the axle pair. The lowcurrent dual link power supply is optional and intended to supply aredundant supply to the microcontrollers in both brake units with atleast single (but preferably double) protection to avoid the risk of acommon short-circuit to be catastrophic for both brake units. With thisdual supply, the software in a brake unit losing primary battery supplyvoltage will not be disturbed and the switchover time will be short.With a hardware battery supply detection activated and monitored by thesoftware, the switchover time will be essentially zero. The switch on ofthe secondary supply and of safety critical electromechanical devicesshall not occur for a single fault in software or hardware. At least twoswitches in serial connection to each device are used to avoid oneshort-circuit failure destroying the switch off function. At least twoindependent software activations are necessary to activate any of thesefunctions. First, the supervisor module supplies the power driversupply, through the safe signal driver supply (toggling at specifiedfrequency), with a software generated signal. A common signal providesactivations for all power drivers. For safety critical designssupervisory functions require that the supervisory (watchdog) functionuse a separate clock circuit. The supervisor module in this case may usethe clock of the other brake unit of the axle pair as this second clocksource through the dual link communication. Second, the main controlmodule controls the power driver with a direct signal to the input pinsof the power driver.

The dual link communication may also be used (1) to transfer brakesystem network information to the brake unit in the axle pair that haslost the connection to the brake system network, (2) to performcrosschecking of the timing (see above) and decision making for thesupervisory function, (3) to transfer information regarding the powersupply status of the brake units for the decision when to supply batterypower across the dual link power supply, and/or (4) to transfer statusinformation at high speed across the axle pair to be used when thecommunication to one brake unit is lost. This information will behelpful for the brake system to decide what actions to be taken by theother brake units when communication to a single brake unit is lost. Thedual link monitoring is an optional way to determine the status of afailed brake unit from a sensor of a critical condition of the failedbrake unit. The sensor could be at least one of temperature, clampingforce, frictional force, brake torque, wheel speed or any other signalof great safety critical importance. The sensor will be supplied throughthe dual link low power supply which is necessary for this option. Thisoption is intended to increase the possibility to continue driving avehicle with a brake system with a failed brake unit by monitoring atleast one critical condition of a failed brake unit through the duallink monitoring.

The components of system 300 are now described in more detail. Primarybattery supply voltage filter, buffer and monitor module 301 providesenergy buffering (e.g., by inclusion of capacitors), EMI-filtering, loadcurrent monitoring and/or load current limitation. Module 301 may alsoprovide reverse battery protection if requested by the power supplysystem, although a perhaps better solution is a fixed cabling system notallowing the user to reverse the battery connection to the individualbrake unit. Logic power supply module 302 supplies voltage for theinternal logic and analog functions (including sensors) of system 300,supplies voltage to communication interfaces, and/or providesshort-circuit protection of each output supply.

Brake system network communication module 303 provides networkcommunication with other units in the brake system and/or with thevehicle systems, while dual link communication module 304 providescommunication across the axle pair (i.e., left side actuator to rightside actuator), including monitoring, crosschecking and watchdogfunctionality and/or transfers brake networking communication when oneactuator in the pair has lost the communication to/from the brake systemnetwork.

Main control module 305 provides the main control strategy for the brakeunit responding to the inputs from brake system network, dual linkcommunication and sensor information connected to the electronic unit.Supervisor module 306 transfers information from the dual linkcommunication module 304 to the main control module 305 and/or performsa watchdog function comparing information from the main control module305 and the dual link communication module 304. If the watchdog functionaccepts the timing and information received according to the rulesspecified by design a software driven safe signal is sent out from thesupervisor module 306. The existence of this signal is necessary toactivate the power driver supply voltage from the safe signal driversupply module 307 described below. A safe signal is defined as a digitalsignal changing from toggling between 0 and 1 at a specified frequency.

Safe signal driver supply module 307 supplies a voltage to the powerdrivers 308 if and only if the safe signal from the supervisor module306 is according to the specified frequency and timing. The supplyvoltage energy is supplied through an analog bandpass filter function.The safe signal driver supply voltage will supply voltage to the powerdrivers 308 as described below.

The power drivers 308 are the buffer drivers used to control the highpower switches 309 (switches can be MOSFET transistor, relay andsimilar). Without a supply voltage the power drivers 308 are not able toswitch on any high power switch 309. The safe signal driver supplyvoltage is the supply voltage to these units. The power drivers 308 arecontrolled by a logic signal from the main control module 305. To switchon a high power switch 309 both the on signal from the main controlmodule 305 and the safe signal driver supply voltage is needed.

High power switches 309 are used to control electromechanical devices310 controlling the function of the brake actuator. The status of thehigh power switches 309 is constantly monitored in order to detect ashort-circuit failure. If the electromechanical device has asafety-critical function the winding/windings to this device arecontrolled by at least two high power switches (as shown in FIG. 3).This redundancy guarantees that the electromechanical device 310 is ableto be switched through the high power switches 309 even if there is asingle failure in a high power switch 309. The decision to switch off toa fail-safe state is taken either by the main control module 305 or thesupervisor module 306 thorough the safe signal to the power driversupply module. Electromechanical devices 310 are in fail-safe conditionwith no current in the windings.

High current dual link power supply module 311 includes at least one ofthe following features: current monitoring of the current flow in thedual link high power supply; current limitation; voltage monitoring ofthe brake on the other side; and a high power switch of the power supplyfrom the primary supply battery voltage to the dual link high powersupply connection to the brake unit on the other side of the axle pair.The switch is normally off, and may comprise either one bi-directionalswitch, one unidirectional switch or two unidirectional switches (one ineach direction). The decision as to when to switch on theswitch/switches can be totally controlled from software, totallycontrolled from hardware monitoring or a combination of hardware andsoftware decision.

Low current dual link power supply 312 includes at least one of thefollowing features: a bi-directional switch of the power supply from thelogic supply voltage to the dual link low power supply connection to thebrake unit on the other side of the axle pair (which bi-directionalswitch is normally on); current monitoring of the current flow in thedual link low power supply; and current limitation. The dual link lowpower supply supplies a second source of power to at least one of thefollowing functions in the brake unit on the other side of axle pair:the core of the main control function; the dual link interface; and,sensors and hardware signal condition to these sensors that are ofimportance at a loss of functionality.

Sensor interface module 313 provides hardware and/or softwareconditioning of sensor signals from at least one of motor position,motor velocity, clamping force, friction force, temperature, braketorque, wheel speed, tire pressure, motor and electromagnet current,etc. Dual link monitoring module 314 monitors information from the brakeunit at the other side of the axle pair at a loss of functionality,including the dual link communication in that other brake unit. Theinformation is used to determine what the brake system shall and can doto keep the vehicle safe and stable on the road in the case of a failureof a single brake unit.

Referring now to FIG. 4, an electrically controlled braking system 10′in accordance with another embodiment of the present invention is shown.Braking system 10′ includes at least one control unit 12 which generatescontrol signals. Braking system 10′ also includes a plurality of brakecomponents 14, 16, 18, 20, 22, 24. In this embodiment, brake components14, 16 are associated with a tractor (schematically illustrated by box40), while brake components 18, 20, 22, 24 are associated with a trailer(schematically illustrated by box 42). While tractor 40 is shown ashaving two brake components and trailer 42 is shown as having four brakecomponents, it should be understood that both tractor 40 and trailer 42may include a greater or lesser number of brake components. Tractor 40and trailer 42 are connected by a trailer link (schematicallyillustrated by box 44), which as is known in the art, are typically usedsuch that control signals and power may be exchanged between tractor 40and trailer 42.

Each of brake components 14, 16, 18, 20, 22, 24 is responsive to thecontrol signals generated by control unit(s) 12. More particularly, eachof brake components 14, 16, 18, 20, 22, 24 includes a brake actuator 26incorporating an electronic control unit 28 which electronic controlunit 28 causes brake actuator 26 to operate in response to the controlsignals. As such electronically controllable brake components are knownin the art, a detailed discussion of the operation thereof is notpresented herein. Each of brake components 14, 16, 18, 20, 22, 24 may beactuated by electrical force, hydraulic force, pneumatic force,combinations of these, and/or by any other appropriate force.

Braking system 10′ includes at least two control networks fortransmitting control signals from control unit(s) 12 to each of brakecomponents 14, 16, 18, 20, 22, 24, with some of brake components 14, 16,18, 20, 22, 24 being electrically connected to control unit(s) 12 viaone control network and others of brake components 14, 16, 18, 20, 22,24 being electrically connected to control unit(s) 12 via another orother control network(s).

In braking system 10′ shown in FIG. 4, two control networks 30′, 32′ areprovided. First control network 30′ electrically connects controlunit(s) 12 with first brake component 14, fourth brake component 20 andsixth brake component 24. Thus, first control network 30′ is adapted totransmit the control signals from control unit(s) 12 to first brakecomponent 14, fourth brake component 20 and sixth brake component 24.Second control network 32′ electrically connects control unit(s) 12 withsecond brake component 16, third brake component 18 and fifth brakecomponent 22. Thus, second control network 32′ is adapted to transmitthe control signals from control unit(s) 12 to second brake component16, third brake component 18 and fifth brake component 22. It will benoted that in this arrangement, the brake components located on theright side of tractor 40 and the brake components on the left side oftrailer 42 are controlled by one control network 30′, while the brakecomponents located on the left side of tractor 40 and the brakecomponents on the right side of trailer 42 are controlled by the othercontrol network 32′. This arrangement is desirable so that should acomplete failure occur in one of control networks 30′, 32′, braking maystill be controlled on both sides of the vehicle, rather than brakingonly being controlled on one side thereof. Of course, it is possiblethat first control network 30′ electrically connects control unit(s) 12with first brake component 14, third brake component 18 and fifth brakecomponent 22, while second control network 32′ electrically connectscontrol unit(s) 12 with second brake component 16, fourth brakecomponent 20 and sixth brake component 24 such that no “cross-linked”connection is provided.

It is desirable that no brake component is directly electricallyconnected to both of first control network 30′ and second controlnetwork 32′. This is true so as to reduce the likelihood that anexternal catastrophic event, such as a tire explosion, in the vicinityof one of the brake components cut the network cabling and/or causes ashort-circuit in both control networks 30′, 32′, thereby causing theentire brake system 10′ to fail. For example, an external catastrophicevent occurring in the vicinity of first brake component 14 may causedamage to first control network 30′, thereby causing first controlnetwork 30′ to be shorted and fail. However, because second controlnetwork 32′ is not directly electrically connected to first brakecomponent 14, such an external catastrophic event likely would not causedamage to second control network 32′, and second control network 32′would still function.

Brake system 10′ also includes an auxiliary control link 46 betweenfirst control network 30′ and second control network 32′, whichauxiliary control link 46 is activatable to electrically connect thecontrol networks 30′, 32′ when a failure occurs in one of the controlnetworks 30′, 32′. The auxiliary control link 46 is adapted to transmitthe control signals to brake components usually controlled by thefailing one of control networks 30′, 32′ when such a failure occurs. Inthe embodiment shown in FIG. 4, one such auxiliary control link 46 isshown. It is preferable that the auxiliary control link 46 be located intrailer link 44. This allows for easy retro-fit of existing systems inorder to provide the benefits of the present invention. For example, theauxiliary control link 46 may be embodied in an adapter unit that isdisposed between the trailer link connections on tractor 40 and trailer42, such that no modification of tractor 40 or trailer 42 is required toimplement the present invention.

It should be recognized that for system 10′ to properly function,control signals for all brake components 14, 16, 18, 20, 22, 24 shouldbe transmitted over both control networks 30′, 32′, not just the controlsignals for the brake components directly connected to each individualcontrol network 30′, 32′. For example, although fourth brake component20 is not directly connected to second control network 32′, the controlsignals for fourth brake component 20 should be transmitted over secondcontrol network 32′, so that in the event of a failure of first controlnetwork 30′ (to which fourth brake component 20 is attached), controlsignals may be transmitted to fourth brake component 20 through secondcontrol network 32′ via auxiliary control link 46.

Thus, as discussed in the above example, suppose that an externalcatastrophic event occurs in the vicinity of first brake component 14which causes damage to first control network 30′, thereby causing firstcontrol network 30′ to be shorted and/or fail. Because second controlnetwork 32′ is not directly electrically connected to first brakecomponent 14, such an external catastrophic event likely would not causedamage to second control network 32′, and second control network 32′would still function. Since fourth brake component 20 and sixth brakecomponent 24 would no longer be receiving control signals through firstcontrol network 30′, auxiliary control link 46 would attempt to supplycontrol signals from second control network 32′ to first control network30′ (or at least the portion thereof which may still transmit signals).Of course, due to the hypothetical external catastrophic event, firstbrake component 14 may be damaged or destroyed and not functionproperly, and may thus not be operational. However, fourth brakecomponent 20 and sixth brake component 24 are likely not damaged—theyare simply no longer receiving control signals through the failed firstcontrol network 30′. As such, control signals supplied to the stillfunctioning portion of first control network 30′ (including fourth brakecomponent 20 and sixth brake component 24) from second control network32′ through auxiliary control link 46 could be used to control fourthbrake component 20 and sixth brake component 24.

Thus, system redundancy is provided, while at the same time isolation ofthe control networks 30′, 32′ from one another is maintained byproviding a buffer (i.e., auxiliary control link 46) therebetween. Thus,it is extremely unlikely that both control networks 30′, 32′ will fail.At the same time, if one of them does fail, control of at least some ofthe brake components on the failed control network can still bemaintained.

In some cases, it may be desirable for two control units 12 to beprovided. When such is the case, one of control units 12 may beelectrically connected to first control network 30′, while the other ofcontrol units 12 may be electrically connected to second control network32′. Alternatively, in order to maintain true redundancy (for example,if one of control units 12 fails), each of the two control units 12 maybe electrically connected to both control networks 30′, 32′. In othercases, it may be desirable for a single control unit 12 to be provided,which control unit 12 may be electrically connected to both controlnetworks 30′, 32′. Of course, in any case where control unit(s) 12is/are connected to both control networks 30′, 32′, it would bedesirable to provide control unit(s) 12 with safeguard measures toensure that shorting or other failure of one control network 30′, 32′does not short or otherwise cause a failure of the entire controlunit(s) 12.

Referring now to FIG. 5, an electrically controlled braking system 10″in accordance with another embodiment of the present invention is shown.Braking system 10″ includes at least one control unit 12 which generatescontrol signals. Braking system 10″ also includes a plurality of brakecomponents 14, 16, 18, 20, 22, 24. Each of brake components 14, 16, 18,20, 22, 24 is responsive to the control signals generated by controlunit(s) 12. More particularly, each of brake components 14, 16, 18, 20,22, 24 includes a brake actuator 26 incorporating an electronic controlunit 28 which electronic control unit 28 causes brake actuator 26 tooperate in response to the control signals. As such electronicallycontrollable brake components are known in the art, a detaileddiscussion of the operation thereof is not presented herein. Each ofbrake components 14, 16, 18, 20, 22, 24 may be actuated by electricalforce, hydraulic force, pneumatic force, combinations of these, and/orby any other appropriate force.

Braking system 10″ includes at least one control network 48 fortransmitting control signals from control unit(s) 12 to each of brakecomponents 14, 16, 18, 20, 22, 24. Control network 48 electricallyconnects brake components 14, 16, 18, 20, 22, 24 to control unit(s) 12in a serial fashion as follows: control unit(s) 12 is/are connected tofirst brake component 14, first brake component 14 is connected to thirdbrake component 18, third brake component 18 is connected to fifth brakecomponent 22, fifth brake component 22 is connected to sixth brakecomponent 24, sixth brake component 24 is connected to fourth brakecomponent 20, and fourth brake component 20 is connected to second brakecomponent 16. During normal operation, control signals are supplied bycontrol unit(s) 12 to brake components 14, 16, 18, 20, 22, 24 asindicated by arrow 50, which control signals travel clockwise when theelements are disposed as schematically shown in FIG. 5.

Brake system 10″ also includes an auxiliary control link 52 betweencontrol unit(s) 12 and the last brake component in the chain of seriallyconnected brake components (second brake component 16 in the embodimentshown in FIG. 5), which auxiliary control link 52 is activatable toelectrically connect control unit(s) 12 to the chain of brake componentswhen a failure occurs in the control networks 48. During failsafeoperation, control signals are supplied by control unit(s) 12 to brakecomponents 14, 16, 18, 20, 22, 24 as indicated by dashed arrow 52, whichcontrol signals travel counterclockwise when the elements are disposedas schematically shown in FIG. 5. It should be recognized that forsystem 10″ to properly function, control signals for all brakecomponents 14, 16, 18, 20, 22, 24 should be transmitted throughauxiliary control link 52.

Thus, suppose that an external catastrophic event occurs in the vicinityof fifth brake component 22 which causes damage to control network 48 inthe area of fifth brake component 22. Those brake components downstreamof fifth brake component 22 (i.e., sixth brake component 24, fourthbrake component 20 and second brake component 16), would no longer bereceiving control signals. In this event, auxiliary control link 52would attempt to supply control signals from control unit(s) 12 to thesebrake components 16, 20, 24. Of course, due to the hypothetical externalcatastrophic event, fifth brake component 22 may be damaged or destroyedand not function properly, and may thus not be operational. However,first brake component 14 and third brake component 18 would stillreceive control signals in the ordinary manner (i.e., clockwise asrepresented by arrow 50), while second brake component 16, fourth brakecomponent 20 and sixth brake component 24 would receive control signalsvia auxiliary control link 52 (i.e., in a counterclockwise direction).Thus, system redundancy is provided.

In all embodiments, in addition to controlling standard brakingoperations, control unit(s) 12 may control various additional brakingfunctions, such as antilock brake systems (ABS) and electronic brakingforce distribution (EBV) systems, as well as other vehicle systems, suchas vehicle suspension and dynamic stability systems.

The present invention, therefore, provides an electrically controlledbraking system which is intended for use with wheeled vehicles, whichincorporates enhanced safety features, which employs system redundancyin case of partial system failure, which is relatively uncomplicated andless costly as compared to known systems, and which is not prone tocomplete system failure in the case of an external catastrophic event.

Although the invention has been described with reference to a particulararrangement of parts, features and the like, these are not intended toexhaust all possible arrangements or features, and indeed many othermodifications and variations will be ascertainable to those of skill inthe art.

1. An electrically controlled braking system comprising: at least one control unit, said at least one control unit generating control signals indicative of demand for braking; a first brake component responsive to the control signals generated by said at least one control unit; a second brake component responsive to the control signals generated by said at least one control unit; a first control network electrically connecting said at least one control unit and said first brake component, said first control network adapted to transmit the control signals from said at least one control unit to said first brake component; a second control network electrically connecting said at least one control unit and said second brake component, said second control network adapted to transmit the control signals from said at least one control unit to said second brake component; an auxiliary control link to electrically connecting said first control network and said second control network, said auxiliary control link adapted to transmit the control signals between said first control network and said second control network when a failure occurs in one of said first control network or said second control network; a third brake component responsive to the control signals generated by said at least one control unit, said third brake component electrically connected to said second control network; a fourth brake component responsive to the control signals generated by said at least one control unit, said fourth brake component electrically connected to said first control network; and wherein said first brake component and said second brake component are located on a tractor and said third brake component and said fourth brake component are located on a trailer connected to the tractor.
 2. The braking system of claim 1 wherein said at least one control unit comprises two control units, wherein one of said two control units is electrically connected to said first control network, and wherein another of said two control units is electrically connected to said second control network.
 3. The braking system of claim 1 wherein said at least one control unit comprises a single control unit, and wherein the single control unit is electrically connected to both said first control network and said second control network.
 4. The braking system of claim 1 wherein said at least one control unit comprises two control units, and wherein each of the two control units is electrically connected to both said first control network and said second control network.
 5. The braking system of claim 1 further comprising a trailer link by which the tractor and the trailer are connected, and wherein said auxiliary control link comprises part of the trailer link.
 6. The braking system of claim 5 wherein the trailer link comprises an adapter connectable between the tractor and the trailer.
 7. The braking system of claim 1 further comprising: a fifth brake component responsive to the control signals generated by said at least one control unit, said fifth brake component electrically connected to said second control network; a sixth brake component responsive to the control signals generated by said at least one control unit, said sixth brake component electrically connected to said first control network; and wherein said fifth brake component and said sixth brake component are located on the trailer.
 8. The braking system of claim 1 wherein each of said first brake component and said second brake component comprises a brake actuator comprising an electrical control unit.
 9. The braking system of claim 1 wherein said first brake component and said second brake component are actuated by a force selected from the group consisting of an electrical force, a hydraulic force, a pneumatic force and combinations of these.
 10. The braking system of claim 1 wherein said first brake component and said second brake component are disposed on a common axle of a vehicle.
 11. The braking system of claim 1 wherein said at least one control unit further controls functions a vehicle system selected from the group consisting of an antilock brake system, an electronic braking force distribution system, a vehicle suspension system, a dynamic stability system and combinations of these.
 12. The braking system of claim 1 wherein control signals to which both said first brake component and said second brake component are responsive are transmitted over both said first control network and said second control network.
 13. An electrically controlled braking system comprising: at least one control unit, said at least one control unit generating control signals indicative of demand for braking; a first brake component, a second brake component, a third brake component, a fourth brake component, a fifth brake component and a sixth brake component, each of which is responsive to the control signals generated by said at least one control unit, said first and second brake components being located on a tractor and said third, fourth, fifth and sixth brake components being located on a trailer connected to the tractor; a first control network electrically connecting said at least one control unit and said first brake component, said fourth brake component and said sixth brake component, said first control network adapted to transmit the control signals from said at least one control unit to said first, fourth and sixth brake components; a second control network electrically connecting said at least one control unit and said second brake component, said third brake component and said fifth brake component, said second control network adapted to transmit the control signals from said at least one control unit to said second, third and fifth brake components; and an auxiliary control link to electrically connecting said first control network and said second control network, said auxiliary control link adapted to transmit the control signals between said first control network and said second control network when a failure occurs in one of said first control network or said second control network.
 14. The braking system of claim 13 further comprising a trailer link by which the tractor and the trailer are connected, and wherein said auxiliary control link comprises part of the trailer link.
 15. The braking system of claim 14 wherein the trailer link comprises an adapter connectable between the tractor and the trailer.
 16. An electrically controlled braking system comprising: at least one control unit, said at least one control unit generating control signals indicative of demand for braking; a first brake component responsive to the control signals generated by said at least one control unit; a second brake component responsive to the control signals generated by said at least one control unit; a control network electrically connecting said at least one control unit and said first brake component, and said first brake component and said second brake component, said control network adapted to transmit the control signals from said at least one control unit to said first brake component and said second brake component; an auxiliary control link electrically connecting said at least one control unit and said second brake component, said auxiliary control link adapted to transmit the control signals between said at least one control unit and said second brake component when a failure occurs in said control network; a third brake component and a fourth brake component responsive to the control signals generated by said at least one control unit, said third brake component and said fourth brake component electrically connected between said first brake component and said second brake component; and a fifth brake component and a sixth brake component responsive to the control signals generated by said at least one control unit, said fifth brake component and said sixth brake component electrically connected between said first brake component and said second brake component.
 17. The braking system of claim 16 wherein said at least one control unit comprises a single control unit, and wherein the single control unit is electrically connected to said control network.
 18. The braking system of claim 16 wherein said at least one control unit comprises two control units, and wherein each of the two control units is electrically connected to said control network.
 19. The braking system of claim 16 wherein each of said first brake component and said second brake component comprises a brake actuator comprising an electrical control unit.
 20. The braking system of claim 16 wherein said first brake component and said second brake component are actuated by a force selected from the group consisting of an electrical force, a hydraulic force, a pneumatic force and combinations of these.
 21. The braking system of claim 16 wherein said first brake component and said second brake component are disposed on a common axle of a vehicle.
 22. The braking system of claim 16 wherein said at least one control unit further controls functions a vehicle system selected from the group consisting of an antilock brake system, an electronic braking force distribution system, a vehicle suspension system, a dynamic stability system and combinations of these.
 23. An electrically controlled braking system comprising: at least one control unit, said at least one control unit generating control signals indicative of demand for braking; a plurality of brake components responsive to the control signals generated by said at least one control unit; a control network electrically connecting said at least one control unit and said plurality of brake components in series in a communications chain, said control network adapted to transmit the control signals in a first direction along the communications chain from said at least one control unit to a first brake component in the communications chain, through any intermediate brake components in the communications chain and to a last brake component in the communications chain; and an auxiliary control link electrically connecting said at least one control unit and the last brake component in the communications chain, said auxiliary control link adapted to transmit the control signals from said at least one control unit to the last brake component in the communications chain and through said control network when a failure occurs in said control network, and in a second direction along the communications chain opposite to the first direction.
 24. The braking system of claim 23 wherein said plurality of brake components comprises four brake components.
 25. The braking system of claim 23 wherein said plurality of brake components comprises six brake components.
 26. The braking system of claim 23 wherein said at least one control unit comprises a single control unit, and wherein the single control unit is electrically connected to said control network.
 27. The braking system of claim 23 wherein said at least one control unit comprises two control units, and wherein each of the two control units is electrically connected to said control network.
 28. The braking system of claim 23 wherein each of said plurality of brake components comprises a brake actuator comprising an electrical control unit.
 29. The braking system of claim 23 each of said plurality of brake components is actuated by a force selected from the group consisting of an electrical force, a hydraulic force, a pneumatic force and combinations of these.
 30. The braking system of claim 23 wherein said at least one control unit further controls functions a vehicle system selected from the group consisting of an antilock brake system, an electronic braking force distribution system, a vehicle suspension system, a dynamic stability system and combinations of these. 